Image sensor device and manufacturing method for improving shutter efficiency

ABSTRACT

A semiconductor device includes a semiconductive substrate and a gate structure over the semiconductive substrate. The semiconductive substrate includes a photo-sensitive region adjacent to the gate structure, and the gate structure is configured to store electric charge generated from the photo-sensitive region. The semiconductor device also includes a conductive structure over the semiconductive substrate. The conductive structure circumscribes and is spaced apart from a sidewall of the gate structure.

PRIORITY CLAIM AND CROSS-REFERENCE

This application claims priority to U.S. patent application Ser. No.62/550,876 filed 28 Aug. 2017, the disclosure of which is herebyincorporated by reference in its entirety.

BACKGROUND

As technologies evolve, complementary metal-oxide semiconductor (CMOS)image sensors attract more and more attention due to their performanceadvantages. For example, CMOS image sensors can provide higher imageacquisition rates, lower operating voltages, lower power consumption andgreater noise immunity. A CMOS image sensor typically comprises an arrayof light-sensing elements or pixels. Each of the pixels is configured toconvert received photons into electrons. Additionally, the CMOS imagesensor comprises circuitry to transform the electrons into electricalsignals. The electrical signals are then processed to generate an imageof a subject scene.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. Specifically, the dimensions ofthe various features may be arbitrarily increased or reduced for clarityof discussion.

FIGS. 1 to 10 are cross-sectional views of intermediate stages of amethod of manufacturing a semiconductor device, in accordance with someembodiments.

FIG. 10A is a schematic top view of a gate structure of thesemiconductor device shown in FIG. 10, in accordance with someembodiments.

FIGS. 11 to 13 are cross-sectional views of additional intermediatestages of a method of manufacturing a semiconductor device, inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The present disclosure provides structures and manufacturing operationsof an image sensor device according to various embodiments. Theperformance of the image sensor is determined by several factors, suchas the signal-to-noise ratio, sensitivity, and dynamic range.Additionally, shutter efficiency is regarded as an important factor inimproving the image quality. The shutter efficiency, usually inconnection to a global shutter scheme, refers to a measure of how wellthe charges can be stored in the storage gate without beingcontaminated, such as by stray light or stray current. The storage gateis used in the global shutter scheme for temporarily storing thephoto-transformed electrons. Greater shutter efficiency allows the pixelto provide better image quality. Of several approaches to improvingshutter efficiency taken recently by researchers, improved storage gatedesign shows particular promise and is discussed in the presentdisclosure. A metal shield may be utilized to protect the storage gatefrom parasitic light or stray electrons. Accordingly, pixel datarepresented by the electrons stored in the storage gate can providegreater accuracy. In the present disclosure, the manufacturing methodand structure of the storage gate and metal shield are redesigned. Theproposed metal shield structure can provide superior noise-blockingperformance. As a result, the shutter efficiency can be effectivelyincreased.

FIGS. 1 to 10 and FIGS. 11 to 13 are cross-sectional views ofintermediate stages of a method of manufacturing a semiconductor device100, in accordance with some embodiments. The semiconductor device 100can be an image sensor, such as a front-side illumination (FSI) imagesensor or a back-side illumination (BSI) image sensor. The semiconductordevice 100 may include an array of image pixels arranged in rows andcolumns, of which one exemplary pixel is illustrated. Referring to FIG.1, a semiconductive substrate 102 is received or provided. Thesemiconductive substrate 102 includes a semiconductive material such assilicon, germanium, silicon germanium, silicon carbide, galliumarsenide, or the like. Alternatively, the semiconductive substrate 102includes a compound semiconductor having gallium arsenic, galliumphosphide, indium phosphide, indium arsenide, indium antimonide, orcombinations thereof. In other alternatives, the semiconductivesubstrate 102 may include a doped epitaxial layer, a gradientsemiconductive layer, or a semiconductive layer overlaying anothersemiconductive layer of a different type, such as a silicon layer on asilicon germanium layer. The semiconductive substrate 102 may be dopedwith an N-type dopant, such as arsenic, phosphor, or the like, or may bedoped with a P-type dopant, such as boron or the like. In the depictedembodiment, the semiconductive substrate 102 includes bulk silicon dopedwith P-type dopants.

Next, isolation structures 104 and 106 are formed in the semiconductivesubstrate 102. The isolation structures 104 and 106 are used forisolating a pixel area from adjacent pixel areas or features. Theisolation structures 104 and 106 may be trench-type isolation or localoxidation of silicon (LOCOS). The isolation structure 104 may refer to ashallow trench isolation (STI) and the isolation structure 106 may be adeep trench isolation (DTI) in which the DTI 106 has a depth greaterthan the depth of the STI 104. As an exemplary operation formanufacturing the isolation structure 104 or 106, several recesses areformed initially by an etching operation, such as a dry etching, a wetetching, a reactive ion etching (RIE) operation, or the like. Next,isolation materials are filled into the recesses to form the isolationstructures 104 and 106. The isolation materials may be formed ofelectrically insulating materials, such as dielectric materials. In someembodiments, the isolation structures 104 and 106 are formed of oxide,nitride, oxynitride, silicon dioxide, nitrogen-bearing oxide,nitrogen-doped oxide, silicon oxynitride, polymer, or the like. Thedielectric material may be formed using a suitable process such aschemical vapor deposition (CVD), physical vapor deposition (PVD), atomiclayer deposition (ALD), thermal oxidation, UV-ozone oxidation, orcombinations thereof. In some embodiments, a planarization operation,such as grinding or chemical mechanical planarization (CMP) processes,may be used to remove excess materials of the isolation structure 104 or106 and level the top surfaces of the isolation structures 104 or 106with the semiconductive substrate 102. In an embodiment, the isolationstructures 104 and 106 are formed by a single etching and depositionoperation, or they can be formed successively.

Referring to FIG. 2, a photo-sensitive region 112 is formed in thesemiconductive substrate 102. The photo-sensitive region 112 receives ordetects photons, light or radiation incident to the surface of the lightsensitive region 112 and transforms the received photons into electricalcurrent. In an embodiment, the photo-sensitive region 112 includes dopedregions with N-type or P-type dopants. In some embodiments, thephoto-sensitive region 112 may be formed of photo-sensing elements suchas a pinned layer photodiode and a non-pinned layer photodiode. In anembodiment, the photo-sensitive region 112 is comprised of a layeredstructure. For example, the photo-sensitive region 112 may includestacked layers of alternating silicon layer and silicon germanium layer(not separately shown). The alternating silicon layer and the silicongermanium layer may be formed of a superlattice multiple quantum wellstructure. Alternatively, the silicon layer and the silicon germaniumlayer may be formed of a multiple quantum dot matrix.

As shown in FIG. 2, well regions 114, 116 and 118 are also formed in thesemiconductive substrate 102. The well region 114 or 116 may includeP-type or N-type dopants. The well region 116, which refers to afloating diffusion node, is formed as a charge tank to store chargesgenerated by the photo-sensitive region 112. The charges stored in thewell region 116 are read out in a readout operation. In the depictedembodiment, the floating diffusion node 116 has an N-type dopant. Insome embodiments, the floating diffusion region 116 has a dopingconcentration greater than a doping concentration of the semiconductivesubstrate 102. The well region 114 serves as an intermediate charge tankbetween the photo-sensitive region 112 and the floating diffusion node116 in a global shutter scheme and can be regarded an additionalfloating diffusion node. In the depicted embodiment, the floatingdiffusion region 114 has an N-type dopant. In some embodiments, thefloating diffusion region 114 has a doping concentration greater than adoping concentration of the semiconductive substrate 102. The wellregion 118 serves as one source/drain region of a gate structure in areadout circuitry, details of which are provided in subsequentparagraphs. The well region 118 may include P-type or N-type dopants. Inthe depicted embodiment, the well region 118 has an N-type dopant. Insome embodiments, the well region 118 has a doping concentration greaterthan a doping concentration of the semiconductive substrate 102. In anembodiment, the well regions 114, 116 and 118 may be formed by an ionimplantation scheme to implant the dopants, followed by an annealingoperation to activate the implanted dopants.

Subsequently, gate structures 130, 140, 150 and 160 are formed over thesemiconductive substrate 102, as shown in FIG. 3. The gate structures130, 140, 150 and 160 may include a dielectric material 122, 124, 126and 128, respectively, and a gate electrode 132, 134, 136 and 138 overthe respective dielectric material. In an embodiment, the dielectricmaterial 122, 124, 126 or 128 is formed of nitride, oxide, oxynitride,or the like. In an embodiment, the dielectric material 122, 124, 126 or128 includes a high-k material, such as HfO₂, ZrO₂, La₂O₃, Y₂O₃, Al₂O₃,TiO₂, HfSi_(x)O_(y), ZrSi_(x)O_(y), LaSi_(x)O_(y), YSi_(x)O_(y),AlSi_(x)O_(y), TiSi_(x)O_(y) or the like. The dielectric materials 122,124, 126 and 128 may include a same material. In an embodiment, the gateelectrode 132, 134, 136 or 138 includes a conductive material or dopedpolysilicon. The conductive material may be selected from copper,tungsten, aluminum, and other suitable metals. The gate electrodes 132,134, 136 and 138 may include a same material. In an embodiment, the gatestructures 130, 140, 150 and 160 are formed by a same series ofoperations. As an exemplary operation, a blanket dielectric material maybe deposited covering the semiconductive substrate 102. Next, a blanketgate material is formed over the blanket dielectric material. Thedeposition operation may be performed using CVD, PVD, ALD or the like.The dielectric material and the gate material are patterned to form thegate structures 130, 140, 150 and 160 and expose a portion of thesemiconductive substrate 102.

The gate structure 130 is formed between the photo-sensitive region 112and the well region 114. In an embodiment, the gate structure 130 isused as a first transfer gate. Charges transferred from thephoto-sensitive region 112 to the well region 114 are conducted througha proper biasing on the gate electrode 132. The gate structure 140 isdisposed adjacent to the gate structure 130. The gate structure 140 isformed directly above the well region 114. In an embodiment, the gatestructure 140 is used as a storage gate. Charges transferred to the wellregion 114 are carried into the storage gate 140 in a data sensingoperation for a pixel. Under the global shutter scheme, the pixel datafor a certain row of pixels are stored in the respective storage gates.In an embodiment, the gate electrode 134 is a floating gate in which thecharges move into or leave the gate electrode 134 of the storage gate140 though the quantum tunneling effect. In an embodiment, the gateelectrode 134 of the gate structure 140 has a width less than the widthof the well region 114 and is covered by the well region 114.

The gate structure 150 is disposed between the storage gate 140 and thegate structure 160. The gate structure 150 is disposed between the wellregion 114 and the floating diffusion node (region) 116. In anembodiment, the gate structure 150 serves as a second transfer gate andis configured to enable transferring of the charges from the gateelectrode 134 to the floating diffusion node 116 through appropriatebiasing on the gate electrode 136. After the data sensing is completed,the charges in each pixel are read out from the respective floatingdiffusion node 116. The gate structure 160 may be part of a readoutcircuitry, such as a reset gate. The source/drain region 118 is used toreceive charges in conjunction with the gate electrode 138 during datareadout. Charges stored in the floating diffusion node 116 may move to asensing circuit through the channel under the gate electrode 138 and thesource/drain region 118 during the data readout operation.

Referring to FIG. 4, a dielectric film 152 is deposited over thesemiconductive substrate 102. The dielectric film 152 conformally coversthe gate structures 130, 140, 150, and 160. In an embodiment, thedielectric film 152 serves as an etch stop layer. The dielectric film152 may be formed of silicon oxide, silicon nitride, silicon oxynitride,or the like. In some embodiments, the dielectric film 152 may be formedof HfO₂, ZrO₂, La₂O₃, Y₂O₃, Al₂O₃, TiO₂, HfSi_(x)O_(y), ZrSi_(x)O_(y),LaSi_(x)O_(y), YSi_(x)O_(y), AlSi_(x)O_(y), TiSi_(x)O_(y) or the like.The dielectric film 152 may be formed by suitable methods, such asthermal oxidation, CVD, plasma-enhanced CVD (PECVD), PVD, or the like.

FIG. 5 shows the formation of a dielectric layer 162 over thesemiconductive substrate 102. The dielectric layer 162 may be referredto as an interlayer dielectric (ILD). In an embodiment, the dielectriclayer 162 covers the gate structures 130, 140, 150 and 160, and thedielectric film 152. The dielectric layer 162 may include silicon oxide,silicon nitride, silicon oxynitride, or the like. The dielectric layer162 may be formed by a suitable deposition method, such as spin-oncoating, CVD, PVD or the like. Subsequently, an patterning/etchingoperation is performed to form a trench or through hole 143 adjacent tothe gate structure 140. In an embodiment, the through hole 143 ispatterned to laterally surround the gate structure 140 (e.g., as will belater depicted in FIG. 10A). The through hole 143 may extend through thedielectric layer 162 and the dielectric film 152. Thus, the through hole143 contacts an upper surface of the semiconductive substrate 102. In anembodiment, a portion of the well region 114 is exposed through thethrough hole 143. Alternatively, the dielectric film 152 and thedielectric layer 162 are formed of different materials (e.g., the film152 and the layer 162 are formed of nitride and oxide, respectively),and the formation of the through hole 143 may be performed by etchingthrough the dielectric layer 162 with the dielectric film 152 acting asan etch stop layer. The etch of the through hole 143 may thus stop at anupper surface of the dielectric film 152. Further, the through hole 143is defined by an inner sidewall facing the gate structure 140 and anouter sidewall substantially parallel to the inner sidewall. In someembodiments, the inner sidewall of the through hole 143 is substantiallyparallel to the sidewall of the gate structure 140. In an embodiment,when viewed from above, the through hole 143 has a ring shapecircumscribing the gate structure 140. The through hole 143 is to befilled with conductive materials and formed as part of a conductivestructure 148, i.e., the peripheral portion 144 in FIG. 10 (the top viewof the peripheral portion 144 has a ring shape as shown in FIG. 10A).

In addition, the dielectric layer 162 is etched to form a through holeor via 159 over the source/drain region 118. A portion of thesource/drain region 118 is exposed accordingly. Through holes 143 and159 may be formed concurrently by an etching operation, such as a dryetch, a wet etch, a reactive ionic etch (RIE), or combinations thereof.

In FIG. 6, the through holes 143 and 159 are filled with an organicmaterial. In an embodiment, the organic material is selected from aphotoresist material, such as a positive photoresist or a negativephotoresist. In an embodiment, the organic material is a polymericmaterial. The filling of the organic material in the through holes 143and 159 may be performed using CVD, PVD, spin-on coating, or the like.In an embodiment, a planarization operation, such as grinding or CMP,may be utilized to level the filled through holes 143 and 159 and removethe excess organic materials over the semiconductive substrate 102.

Next, the dielectric layer 162 is etched, as illustrated in FIG. 7.Portions of the dielectric layer 162 over the gate structure 140 andover the well region 118 are recessed. A recess 147 is formed and stopsat the dielectric film 152 over the gate electrode 134. As such, aportion of the dielectric film 152 over the gate electrode 134 isexposed. In an embodiment, the recess 147 has a circular shape or apolygonal shape, such as a rectangle, from a top view perspective. Therecess 147 may possess a shape following the pattern of the gateelectrode 134 while having a greater area for completely covering thegate electrode 134. In an embodiment, the recess 147 has sidewallsextending beyond the outer sidewalls of the through hole 143 and thuscompletely covers the through hole 143. Moreover, a portion of thedielectric layer 162 remains between the through hole 143 and the gateelectrode 134 during the etch of the recess 147. The remainingdielectric layer 162 below the recess 147 has a top surface leveled withthe upper surface of the filled through hole 143. In an embodiment, arecess 149 is formed over the through hole 159. In an embodiment, therecess 149 has a size greater than the size of the through hole 159 froma top view perspective. The recess 147 or 149 may be formed by a wetetch, a dry etch, or an RIE operation. The recess 149 may be formedduring a same etching operation for the recess 147, or the recesses 147and 149 can be formed successively.

Referring to FIG. 8, the organic materials in the through holes 143 and159 are removed. A bottom surface of the through hole 143 and a bottomsurface of the trench 159 are exposed accordingly. The removal of theorganic material can be performed using a wet etch, a dry etch or an RIEoperation. In the depicted embodiment, a solvent is utilized to dissolveand remove the organic material. A post-cleaning operation may beperformed to ensure complete removal of the residual organic material.

After the through holes 143 and 159 are emptied, a conductive structure148 is formed in the recess 147 and the through hole 143, asdemonstrated in FIG. 9. The conductive structure 148 may be formed by aconductive material such as titanium, tantalum, titanium nitride,tantalum nitride, copper, copper alloys, nickel, tin, gold, orcombinations thereof. The conductive structure 148 includes a topportion 142 and a peripheral portion 144 occupying the spaces of therecess 147 and the through hole 143, respectively. In an embodiment, thetop portion 142 is connected with the peripheral portion 144 from alower surface of the top portion 142. In an embodiment, the top portion142 of the conductive structure 148 covers the gate structure 140. In anembodiment, the peripheral portion 144 circumscribes the sidewall of thegate structure 140. In an embodiment, the peripheral portion 144 has aheight H1, measured from the surface of the semiconductive substrate 102to a lower surface of the top portion 142, substantially equal to aheight of the gate structure 140. In an embodiment, the peripheralportion 144 is disposed proximal to and substantially parallel to thesidewall of the gate structure 140. In an embodiment, the top portion142 contacts the dielectric film 152 around a top surface of the gateelectrode 134. In an embodiment, the top portion 142 covers a topsurface of the gate electrode 134. In an embodiment, the dielectric film152 laterally surrounds the peripheral portion 144 of the conductivestructure 148 adjacent to the semiconductive substrate 102. Theconfiguration of the proposed conductive structure 148 can providebetter protection of the storage gate 140 from external noise, such asundesired light or electric current. The accuracy of the pixel datarepresented by the charges contained in the storage gate 140 can bebetter maintained. Moreover, a conductor including a conductive via 155and a conductive pad 176 over the conductive via 155 is formed in therecess 159 and the through hole 149. In an embodiment, the conductivevia 155 and the conductive pad 176 have a conductive material similar tothat of the conductive structure 148. In an embodiment, the conductivepad 176 has an area greater than the area of the conductive via 155 froma top view perspective. In an embodiment, the conductive pad 176 atleast partially overlaps the conductive via 155. The conductivestructure 148, the conductive via 155 and the conductive pad 176 may beformed by any suitable methods, such as CVD, PVD, ALD, sputtering, orthe like.

The through hole 143 or the peripheral portion 144 adjacent to the gateelectrode 134 is spaced apart from the sidewall of the gate electrode134. In an embodiment, the dielectric material 162 fills spaces betweenthe peripheral portion 144 and the gate electrode 134. The geometry ofthe width of the through hole 143 is determined as a process-friendlydimension such that a desirable etching operation for forming thethrough hole 143 and a subsequent filling operation for forming theperipheral portion 144 can be realized successfully. For one thing,existing schemes that completely remove the dielectric material 162 overand on sidewalls of the gate electrode 134 to create spaces for theconductive structure 148. However, such a removal operation is usuallyunsuccessful due to the narrowed width of the spaces toward the bottomof the gate electrode 134. The narrowed width may not be processfriendly, where residues of the dielectric layer 162 may remain near thebottom of the gate electrode 134 after the etching operation due toloading effect. As a result, the remaining residual dielectric material162 may deteriorate the filling performance of conductive materials inthe spaces (e.g., generate voids/opening around the gate electrode).Embodiments in accordance with the instant disclosure may provide awell-managed formation operation at the peripheral portion 144 to form areliable conductive structure (e.g., structure 148) around the gateelectrode 134 without void or opening.

Referring to FIGS. 10 and 10A, a conductive plug 154 is formed in thetop portion 142. An insulating material 168 may be formed such that theconductive plug 154 is electrically insulated from the remaining portionof the top portion 142 by the insulating material 168. In operation, theconductive plug 154 receives a biasing voltage and is configured toattract charges in the well region 114 toward the gate electrode 134 ofthe storage gate 140 during an image sensing operation. In anembodiment, the insulating material includes dielectric materials suchas silicon nitride, silicon oxide, silicon oxynitride, or the like. Inan embodiment, the dielectric materials include a high-k material, suchas HfO₂, ZrO₂, La₂O₃, Y₂O₃, Al₂O₃, TiO₂, HfSi_(x)O_(y), ZrSi_(x)O_(y),LaSi_(x)O_(y), YSi_(x)O_(y), AlSi_(x)O_(y), TiSi_(x)O_(y) or the like.The insulating material 168 may be formed by initially etching the topportion 142. The etching operation forms an enclosing trench patternthat runs through the thickness of the top portion 142 and reaches thedielectric material 152. FIG. 10A shows a top view of the gate structure140 in which the cross-sectional view of FIG. 10 is drawn from thesectional line A-A′ of FIG. 10A. In the depicted example, the topportion 142 of the conductive structure 148 covers the top surface ofthe gate electrode 134 of the gate structure 140 from a top viewperspective. In an embodiment, the insulating material 168 has a ringshape from a top view perspective and consists of concentric circlesoverlapping the gate electrode 134. Next, the insulating material 168 isdeposited into the etched trench of the top portion 142 to form a ringelectrically insulating the top portion 142 and the conductive plug 154.

FIG. 11 shows the formation of another dielectric layer 164 over thedielectric layer 162. The dielectric layer 164 may be referred to as anadditional interlayer dielectric (ILD). The dielectric layer 164 mayinclude silicon oxide, silicon nitride, silicon oxynitride, or the like.The dielectric layer 164 may be formed by a suitable deposition method,such as spin-on coating, CVD, PVD or the like. Subsequently, conductivevias 156 and 158 are formed in the dielectric layer 164. As an exemplaryoperation, the dielectric layer 164 is recessed and the trenches areformed over the gate structure 140 and the well region 116. The trenchfacing the well region 116 may further run through the dielectric layer162 and reach the well region 116. Subsequently, a conductive materialis deposited in the trenches to construct the conductive vias 156 and158 in place. In an embodiment, the conductive vias 156 and 158 may beformed of a conductive material such as titanium, tantalum, titaniumnitride, tantalum nitride, copper, copper alloys, nickel, tin, gold, orcombinations thereof, through a deposition approach such as CVD, PVD,ALD, or the like.

Next, an interconnect layer 165 is formed over the dielectric layer 164as shown in FIG. 12. The interconnect layer 165 is configured toelectrically couple the components in the semiconductive substrate 102and the dielectric layers 162 and 164 with external devices. In somecases, the interconnect layer 165 may establish redistributedconnections for the features in the semiconductive substrate 102 anddielectric layers 162 and 164 for facilitating signal transmission.Thus, the interconnect layer 165 can also be termed a redistributionlayer (RDL). The interconnect layer 165 may include layered conductivelines 161. The conductive lines 161 in each layer extend along ahorizontal direction and are interconnected through adjacent verticalconductive vias or contacts 163. The conductive lines 161 and conductivevias/contacts 163 may be formed of conductive materials, such as copper,tungsten, aluminum, silver, combinations thereof, or the like. Thenumber of layers for conductive lines 161 or conductive vias/contacts163 can be configured in adaptation to different applications asdesired. Furthermore, although not separately shown, one or more metallines and metal vias in the interconnect layer 165 or the dielectriclayers 162 and 164 (e.g., conductive via 156) are established and areelectrically coupled to the conductive plug 154, thereby supplying abiasing voltage to the conductive plug 154.

Referring to FIG. 13, a light pipe 172 is formed in the interconnectlayer 165 and the dielectric layers 162 and 164. The light pipe 172 isconfigured to receive light and direct the received light through theinterconnect layer 165 and the dielectric layers 162 and 164 towards thephoto-sensitive region 112. The light pipe 172 may include resin,spin-on glass, or other suitable transparent or translucent material.The light pipe 172 may be formed by recessing the interconnect layer 165through the dielectric layers 162 and 164, followed by deposition of thelight pipe material 172. A planarization operation, such as grinding orCMP, may be utilized to level the upper surface of the light pipe 172with the interconnect layer 165.

According to an embodiment of the present disclosure, a semiconductordevice includes a semiconductive substrate and a gate structure over thesemiconductive substrate. The semiconductive substrate includes aphoto-sensitive region adjacent to the gate structure, and the gatestructure is configured to store electric charge generated from thephoto-sensitive region. The semiconductor device also includes aconductive structure over the semiconductive substrate. The conductivestructure circumscribes and is spaced apart from a sidewall of the gatestructure.

According to an embodiment of the present disclosure, a semiconductordevice includes a semiconductive substrate and a gate structure over thesemiconductive substrate, where the semiconductive substrate includes aphoto-sensitive region adjacent to the gate structure. The gatestructure is configured to store electric charge generated from thephoto-sensitive region. The semiconductor device further includes aconductive structure covering the gate structure, where the conductivestructure has a peripheral portion having a height substantially equalto a height of the gate structure and being spaced apart from a sidewallof the gate structure.

According to an embodiment of the present disclosure, a method ofmanufacturing a semiconductor device includes: providing asemiconductive substrate; forming a photo-sensitive region in thesemiconductive substrate; forming a gate structure over thesemiconductive substrate; forming a dielectric layer over the gatestructure; forming a first through hole adjacent to and spaced apartfrom a sidewall of the gate structure; filling the first through holewith a material; forming a via in the dielectric layer; removing thematerial to form a second through hole in the dielectric layer; andfilling the via and the second through hole with a same conductivematerial.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A semiconductor device, comprising: asemiconductive substrate; a gate structure over the semiconductivesubstrate, wherein the semiconductive substrate includes aphoto-sensitive region adjacent to the gate structure, and the gatestructure is configured to store electric charge generated by thephoto-sensitive region; a conductive structure over the semiconductivesubstrate, the conductive structure circumscribing and spaced apart froma sidewall of the gate structure; a dielectric film covering the gatestructure; and a dielectric layer laterally surrounding the gatestructure and the dielectric film, wherein the dielectric layercomprises a top surface facing the conductive structure and a bottomsurface facing the semiconductive substrate, a width of the top surfaceof the dielectric layer is greater than a width of the bottom surface ofthe dielectric layer, and a top surface of the dielectric film isexposed through the dielectric layer.
 2. The semiconductor deviceaccording to claim 1, wherein the conductive structure has a top portioncovering a top surface of the gate structure from a top viewperspective.
 3. The semiconductor device according to claim 2, whereinthe conductive structure has a peripheral portion surrounding and spacedapart from the sidewall of the gate structure.
 4. The semiconductordevice according to claim 3, wherein the dielectric layer comprises anouter sidewall facing the peripheral portion of the conductive structureand an inner sidewall facing the sidewall of the gate structure, and anupper portion of the inner sidewall exhibits a curvature greater thanthat of an upper portion of the outer sidewall.
 5. The semiconductordevice according to claim 1, wherein the dielectric film conformallycovers the gate structure.
 6. The semiconductor device according toclaim 5, further comprising a conductive plug extending through theconductive structure and terminating on the dielectric film.
 7. Thesemiconductor device according to claim 1, wherein the dielectric filmextends between the bottom surface of the dielectric layer and thesemiconductive substrate.
 8. The semiconductor device according to claim1, wherein the top surface of the dielectric film is coplanar with anupper surface of the dielectric layer.
 9. The semiconductor deviceaccording to claim 1, wherein the dielectric film contacts a sidewall ofthe gate structure.
 10. A semiconductor device, comprising: asemiconductive substrate; a gate structure over the semiconductivesubstrate, wherein the semiconductive substrate includes a well regionaligned with the gate structure and a photo-sensitive region adjacent tothe gate structure, and the gate structure is configured to storeelectric charge generated by the photo-sensitive region through the wellregion; a conductive structure over the gate structure, the conductivestructure comprising a peripheral portion and a top portion covering theperipheral portion, the top portion comprising a uniform thicknessthroughout an entirety of the top portion and extending beyond theperipheral portion, the peripheral portion having a height substantiallygreater than a height of the gate structure and being spaced apart froma sidewall of the gate structure, and the peripheral portion being incontact with the well region; and a first dielectric layer overlappingthe gate structure and a second dielectric layer laterally surroundingthe first dielectric layer, wherein the second dielectric layercomprises a top portion adjacent to the top portion of the conductivestructure and a bottom portion adjacent to the semiconductive substrate,and the top portion of the second dielectric layer comprises a widthgreater than a width of the bottom portion of the second dielectriclayer.
 11. The semiconductor device according to claim 10, wherein thetop portion of the second dielectric layer is coplanar with a topportion of the first dielectric layer.
 12. The semiconductor deviceaccording to claim 10, further comprising a third dielectric layerlaterally surrounding the conductive structure, wherein the top portionof the conductive structure comprises a bottom surface facing the gatestructure and the peripheral portion, and the third dielectric layer isin contact with the bottom surface of the top portion of the conductivestructure.
 13. The semiconductor device according to claim 10, furthercomprising a conductive plug disposed within and electrically insulatedfrom the conductive structure.
 14. The semiconductor device according toclaim 13, further comprising an interconnect layer disposed over thegate structure and electrically coupled to the conductive plug.
 15. Thesemiconductor device according to claim 14, further comprising a lightpipe extending through the interconnect layer and configured to directphotons to the photo-sensitive region.
 16. A semiconductor device,comprising: a semiconductive substrate; a gate structure over thesemiconductive substrate, wherein the semiconductive substrate includesa photo-sensitive region corresponding to the gate structure, and thegate structure is configured to store electric charge generated by thephoto-sensitive region; a dielectric film conformally covering asidewall and an upper surface of the gate structure; a conductivestructure over the gate structure and the dielectric film, theconductive structure comprising a peripheral portion extending toward asurface of the semiconductive substrate and a top portion covering theperipheral portion; a first dielectric layer filling a space between thedielectric film and the conductive structure; and a conductive plugextending through the top portion, separated from the top portion andterminating on an upper surface of the dielectric film.
 17. Thesemiconductor device according to claim 16, wherein the dielectric filmextends over the semiconductive substrate on a side of the peripheralportion opposite to the gate structure.
 18. The semiconductor deviceaccording to claim 16, wherein the dielectric film contacts a topportion of the gate structure.
 19. The semiconductor device according toclaim 16, further comprising a second dielectric layer between the gatestructure and the semiconductive substrate, wherein the dielectric filmconformally covers sidewalls of the gate structure and the seconddielectric layer.